As environmental problems become increasingly serious in recent years, renewable power sources such as solar cells and wind power generators that are rapidly being put into use are considered to be an effective means of achieving lower carbon emissions and solving the problem of energy resources. However, these types of renewable power sources experience large fluctuations in output. As a result, from the standpoint of the quality of electric power, an adjustment means is indispensable for offsetting the fluctuations in output of the renewable power sources. Thermal power generators, which feature rapid response speed, are currently the chief means used as such adjustment means. As a result, the increased introduction of renewable power sources that have major fluctuation in output may be caught in a dilemma in which thermal power generators need to be used as adjustment means. Obtaining a powerful adjustment means to take the place of thermal power generators is therefore a major issue. As one such adjustment means, the introduction of high-capacity storage batteries (such as sodium sulfur batteries) is effective, but from the standpoint of installation and operating costs, the introduction of high-capacity storage batteries is thought to face extremely high obstacles.
Great strides are being made in research relating to V2G (Vehicle-to-Grid) technology that, by effecting multiple linkage and operation, employs as virtual high-capacity storage batteries for electric power system stabilization: the storage batteries that are mounted in vehicles that run on electric power (hereinbelow referred to as EV (Electric Vehicles) that include hybrid electric vehicles that are equipped with storage batteries together with another motive power source) and that, similar to renewable power sources, are expected to rapidly come into widespread use; and the chargers to which these storage batteries are connected. The V2G proposal itself dates to the 1980s, and research reports estimating the extent of the macro-stabilization effect over an entire electric power system network have been issued continuously. In the past few years, the reports have come to focus on micro-control methods for the concrete construction of a system, i.e., technology for controlling the charging of a multiplicity of EVs individually and in real time.
For example, Non-Patent Document 1 describes a charging/discharging control method for setting, for example, an EV driving model, a power distribution network model, and an electric power price time variation model and implementing optimum scheduling by Particle Swarm Optimization (PSO), which is inspired by the movement of shoal of fishes.
Patent Document 1 describes the configuration of an EV charging planning device and refers to optimum charging scheduling that uses a genetic algorithm.
A case that assumes not only the charging of EVs but also the discharging from the EVs to the distribution network (electric power system side) is typically referred to as V2G. However, a case that assumes only charging of EVs may be referred to distinguish from G2V. G2V is assumed to decrease the load upon the internal storage battery of EVs in proportion to the decrease in the number of charge/discharge cycles.